A well-known problem in regions having hard water (i.e., water comprising a high level of Calcium and/or Magnesium ions) is the formation of scale deposits. Particularly in applications where there are high levels of carbonate and/or phosphate ions the formation of Ca/Mg scales of these species can lead to buildup which prevents heat transfer, restricts or disrupts fluid flow, decreases the operating lifetime or efficiency of equipment, causes unsightly residue (“film”), or combinations thereof. Here and elsewhere, the term “carbonate scale” and “phosphate scale” refer to salts of these species with calcium, magnesium, or other metal ions that are not fully soluble in the conditions in question.
Carbonate and phosphate scale are particularly troublesome in machine dishwashing applications because they lead to unsightly residues, or films, on dishware, tableware and especially glassware. This phenomenon is widely known as “hard water film”. In general, the presence of phosphate and carbonate are desirable in such formulations because of their cleaning power or building power, so they cannot simply be removed from the formula. Hence, “anti-filming technologies” to reduce the formation of carbonate or phosphate scale in automatic dishwashing have been extensively described in the literature.
Typically such anti-filming technologies have comprised polycarboxylates such as polyacrylates, polymethyacrylates, etc. as described in U.S. Pat. No. 5,591,703 and references described therein. Polycarboxylate technologies significantly assist in the reduction of hard water filming in automatic dishwashing, as well as in more general water treatment applications.
Another class of anti-filming materials to reduce phosphate and carbonate scale is the sulfonate/carboxylate copolymers as described in U.S. Pat. No. 5,547,612, U.S. Pat. No. 6,395,185 and references described therein. Commercially available examples of such polymers include Alcosperse® 240 (Alco Chemical), and Acusol® 586 (Rohm & Haas).
The copolymers described in the art are typically derived from combinations of sulfonate-containing and/or carboxylate-containing ethylenically unsaturated monomers, such as acrylic acid, methylallylsulfonic acid, ethoxylate esters of acrylic acids, and variations thereof. A wide variety of such monomers, additional nonionic and/or cationic comonomers, and combinations have been described in the art. The sulfonated monomer is expensive and is the major contributor to the high cost of the polymer containing it. As a result of these polymers' high cost, their application in automatic dishwashing detergents remains limited.
There is a long-standing need for these polymers to become more cost-effective so that they may be used more generally in automatic dishwashing detergents. In addition, though the water-treatment industry has been better able to afford conventional carboxylate/sulfonate functionalized acrylate-type materials, there is also a general need for more cost-effective polymers in this area as well, in order to render plant and other operations more economical.
Further, it is desirable to derive these anti-filming polymers from natural sources that are cheap, plentiful and preferably renewable, such as plants, animals or bacteria.
It has now been surprisingly discovered that effective sulfonate/carboxylate materials for anti-scaling, anti-filming and anti-spotting benefits can be derived by using relatively inexpensive polymeric or oligomeric “templates” and post-functionalizing them with the appropriate carboxylate, sulfonate, and nonionic functionalities.